Wednesday, March 17, 2010

Mclean debunked (at last)

Better late than never, our Comment on McLean has been formally accepted. It has spent most of the last 6 months on the Editor's desk, awaiting the decision. The peer review was painless apart from the time taken - the three reviewers were all positive and made a small number of helpful suggestions which were easily incorporated into the text. However, the time taken (and it could have been months longer) is something that the AGU might like to think about.

Amusingly, the comment will be published alone, without the customary Reply. Why? Because...McLean et al couldn't muster a reply that was publishable (and not for want of trying, either - it was simply rejected). No doubt this will further strengthen their belief in a widespread climate science conspiracy to suppress their groundbreaking research. Hopefully, disinterested observers will conclude instead that there is simply no valid defence of what they did. I have no idea what they tried to say, although the press release at the time of the original publication shows that they were aware of the obvious criticisms and had some wriggling already well prepared. I have emailed them to ask if they will share their response. If their response had been accepted, it would have potentially taken another two months for our (sequential) revisions, and another month of reviewing. All for a short paper which points out glaring errors that should never have made it into print.

Just to go over the science again...it has been well-known for decades that ENSO/SOI is related to interannual temperature variability. It has also been repeatedly shown that this cannot represent more than a modest part of the total temperature variations and a negligible part of the long-term trend. Evidence for all of this is referenced in our Comment. The primary error of McLean et al is that although they filter out all long term changes, they still claim that the resulting high correlation between SOI and global mean temperature (in the filtered series) has relevance for long term trends. As shown in the toy examples in the comment, this is simply not true - the correlations calculated by their analysis method are completely unrelated to any long-term trends in the underlying data. A secondary error is that they splice together two data sets which have different baselines, which artificially reduces the warming by about 0.2C. A third error is that they claim to identify two flat periods with a breakpoint in the middle (for both SOI and temperature), but their statistical analysis provides no support for this.

Update2: Someone purporting to be McLean replies in the comments, confirming that he received my email but is not prepared to share his reply, which seems curiously at odds with his bullish attitude regarding his research. What odds it will be published in that septic journal of last resort bastion of quality, the non-ISI-listed E&E (eds: Boehmer-Cristiansen and Peiser) or not at all?

To be honest it probably does little harm if wrong papers (and even grossly invalid papers) sit in the literature without rebuttal, so long as people ignore them. It is easier (and creates fewer enemies) to just let them sink without trace. But in this case even if no genuine scientist was likely to be taken in by it, there is the inactivist machine to think about.

Well it's not obviously shoddy or bogus (and the authors are real scientists) but I'm sceptical of the result. I don't see where a big enso-related trend in temperature can come from when there has been no big enso trend in the first place.

I'm suspicious of the fact that the number of SST observations has increased hugely over the time period (note the log scale in their plot!), and they specifically say the data in the early period are inadequate to reconstruct the relationship. Maybe the increasing precision over time has allowed the GW signal to leak into the ENSO signal. I'm sure plenty of people will take a good look at it, but for now I'd bet against it standing the test of time.

James,The press release you link to was the third try. The initial one seems to have been by the NZ CSC, but through Marc Morano. There followed another from Australian CSC. After kerfuffle at Tamino's and elsewhere, the third one was released.

I traced all this at the time - it's hard to think of a more egregious example of bogus PR science.

I also showed that the SOI long term trend was of the opposite sign to the temperature record. If anything, it should have led to an overall slight, albeit insignificant cooling trend over 1979-2008 period of the UAH record.

Completely off topic, but I also have an interesting update on the IOP fiasco - it seems IOP Energy Group founder Terri Jackson will be a featured speaker at the upcoming Heartland conference.

Steve - I see you are right, I had just read the middle two lines together!

"19 July 2008 Submitted to the Journal of Climate 16 November 2009 Revised"

I hope (and expect) the reviewers were giving it a careful examination rather than just sitting on it...but I find it hard to believe the result. I'm sure there will be further debate.

PB2, that's an interesting and basically correct article, I've mentioned Goodman here making related points a couple of times previously, and for some reason had just been reading about the ziliak/mcloskey book a few days ago, though I've not actually seen it... One thing that the anti-p-level brigade frequently get wrong is the claim that presenting a confidence interval solves the problem, which actually isn't necessarily true, as I explain here.

Ah, now I remember it was this which piqued my interest recently. I even agree with the cited Armstrong (here), mostly.

Thanks DC, I didn't realise that was actually written after Tamino et al.

Hi JamesI see that the Mclean paper doesn't tell us anything about long term trends. Does it tell us anything about the relationship between ENSO and interannual temperature variability?

Secondly, I too was interested to see the reply by McLean. You have seen it but can't share it? Or it never made it to the review stage?

Finally I wonder if you can just elaborate on "this cannot represent more than a modest part of the total temperature variations". I only ask because the greatest spike in global temperature in recent time came in 1998 when there was the strongest El Nino of recent times. That suggests to me that ENSO can have a relatively large short term effect on temperature. Sorry I'm just a little confused.

It doesn't tell us anything that we didn't already know. In fact the way they mangled the stats makes it hard to get any quantitative interpretation out of their work.

Yes ENSO can have a big effect on the year-to-year variation, with 1998 being the most extreme case on reord. But when you look at the multidecadal time series, ENSO explains little (though Compo and Sardeshmukh's new paper may have something to say about that).

I haven't seen the McLean reply. As I understand it, it went to independent review, and was rejected. I have emailed McLean...no reply yet.

It appears Mclean et al have replied online. Lets ignoring all the stuff about the peer-review process at AGU. The content of their reply that your comment misunderstood that the detrend process was only used to identify the 7 month lag not to show the link between ENSO and temperature seems sound. Do you have any comment on it?

Thanks for that. The short answer is that they directly contradict this bizarre claim by admitting that in fact the statistics were "in the context of the discussion of our derivatives". (You will surely note there is no indication of the heavy processing in the abstract where the statistics are presented.)

In other words, the statistics for %age variance explained were indeed based on differenced data and therefore (as we show) can provide absolutely no support for their claim to have shown "the potential of natural forcing mechanisms to account for most of the temperature variation".

I didn't think it possible: the venue of their response is even worse than "published" in E&E, or unpublished on the arXiv. Instead, it's unpublished at denial-clearinghouse SPPI, interwoven with a rambling persecution complex. And, needless to say, entirely lacking in any cogent rebuttal.

It is evident that Foster et al (including JA) were instrumental in having the response to Foster et al by McLean et al rejected by their own nominated editor and reviewers, it is disingenuous to say the least for JA here to exult that there has been no published response by McLean et al to Foster et al.

You might have a point, were it not for the facts that (a) we did not nominate any editors (and nor did we have the authority to do so) and (b) although (as required) we proposed some suitable reviewers for our Comment, we have absolutely no input into the choice of reviewers for McLean's reply. In any case the choice of reviewers is entirely within the purview of the Editor, we can only make suggestions.

JA: (1) so why was the editor for McLean et al changed for your Foster et al? You and/or your associated authors are on record at Climategate for organising changes in editors. (2) That AGU allows you to nominate "peer reviewers" tells me all I need to know about the integrity of AGU, especially under its new Chair.(3) When I was a young academic, a long time ago admittedly (I ceased being an academic in 1970), I had a few peer-reviewed papers published which elicited responses (eg from the, I assume, sadly defunct Stephen Enke), I was allowed to publish a NON-peer reviewed response (something to do with natural justice). Why did McLean et al have to be submitted by a new editor to new peer reviewers?(4)If McLean et al's response to Foster and you et al is such rubbish, why don't you explain why, POINT by POINT, here? My breath is bated.

1) We did not nominate any editor, only making the suggestion that one of the senior ones took charge. I have no idea which editor was responsible for the original McLean et al and don't see any reason why this person in particular should have been used again.

2) The AGU does not allow nomination of reviewers. It asks for suggestions, which is pretty much ubiquitous across all journals - I can't think of a single one that does not, though perhaps some exist. It is the editor's job to select reviewers.